Food preparation systems are well known in the food science and consumer goods area. Such systems allow a consumer to prepare at home a given type of food, for instance a beverage such as a coffee-based beverage, e.g. an espresso or a brew-like coffee cup.
In the following description, the invention will be described in relation to a its specific application to beverage preparation systems. However, the invention globally encompasses systems for non-beverage items preparation, such as for instance ice cream, soups comprising particles (herbs, croutons, etc.), jellies, dairy items (e.g. yogurts, cream desserts, etc.), or any kind of similar non liquid flowable edible products.
Today, most preparation systems for in-home food and beverage preparation comprise a machine having a so-called “brewing chamber” or “brewing unit” which can accommodate portioned ingredient for the preparation of the food or beverage. A so-called “brewing unit” comprises several parts which are designed to be assembled so as to create a closed cavity wherein the food or beverage ingredient can be placed. The brewing unit comprises means for injecting a preparation medium under pressure such as a fluid which is typically water through the ingredient, so as to prepare a corresponding food or beverage, which is then dispensed out of the brewing unit, to the consumer. The preparation fluid is sourced from a fluid conducting system of the machine to which the brewing unit is connected. The preparation is performed within the brewing unit at a pressure above the atmospheric pressure, which is typically comprised between 1 and 20 bar, preferably between 2 and 15 bar (relative pressure). The preparation can be performed by passing preparation fluid through the ingredient in a loose form or through the ingredient contained in a capsule or pod. For this reason, it is an essential characteristic of a brewing unit to be able to withstand a pressure difference between inside the cavity, and the ambient pressure (which is generally equal or substantially equivalent to atmospheric pressure) without opening itself when pressure inside the cavity increases (typically fluid pressure, e.g. water pressure).
Ingredient portions can be pre-dosed before they are placed into the cavity of the brewing unit, and can take the form of soft pods or pads, or sachets. More and more systems utilize semi-rigid or rigid portions such as rigid pods or capsules. In the following, it will be considered that the beverage machine of the invention is a beverage preparation machine working with a rigid or semi-rigid capsule, or with an ingredient in loose form such as roast and ground coffee grains, to be placed directly into the brewing unit of the machine.
As said above, the so-called “brewing unit” of a machine comprises a receptacle or cavity for accommodating said ingredient, that is for instance contained in a capsule, and a fluid injection system for injecting a fluid, preferably water, under pressure through said ingredient, for instance by piercing through a wall of the capsule that contains the ingredient. Water injected under pressure through the ingredient, for the preparation of a coffee beverage according to the present invention, is preferably hot, that is to say at a temperature above 70° C. However, in some particular instances, it might also be at ambient temperature, or even chilled. The pressure inside the brewing unit during extraction and/or dissolution of the ingredient is typically about 3 to about 8 bar for dissolution products and about 2 to about 12 bar for extraction of roast and ground coffee.
By definition, the brewing unit comprises means to conduct fluid through the ingredient (e.g. fluid injection means such as for instance a needle), and a “closed cavity”, that is to say a cavity that holds the ingredient within said brewing unit, such that said ingredient is not displaced out of said cavity under the effect of fluid passing there through, during the whole food or beverage preparation cycle, and until said ingredient is extracted or dissolved as a final food or beverage that is to be delivered to the consumer through a dispensing opening of said brewing unit. Preferably also, the so-called “closed” cavity of the brewing unit should ensure that no fluid injected therein escapes said brewing unit, except of course as final food or beverage that is to be delivered to the consumer.
In other words, a “brewing unit” comprises all functional elements necessary for holding the ingredient—be it loose, or contained in a capsule or pod—, and directing preparation fluid through and mixing it with said ingredient, during the preparation process and until final product delivery to the consumer. At all steps, the brewing unit resists the pressure difference between inside and outside of its cavity, such that:                fluid can only flow from its entry point into the cavity, through the ingredient, towards the beverage dispensing opening of the cavity,        and in case the ingredient is contained in a capsule or pod, the brewing unit encloses said capsule or pod so as to guarantee that fluid pressure increase therein does not damage the walls of said capsule or pod.        
In food and beverage preparation systems known today, functional elements of the machine can be detached from the main machine body, so that the beverage preparation machine can be made modular and gives the possibility to the consumer to adapt one or the other functional element of the machine to its needs. For instance, it is possible to detach the brewing unit from the beverage machine base, so that it is easier to clean (the brewing unit is usually the functional part of the machine which is in contact with the ingredient or the beverage, and therefore it more likely to need regular maintenance and cleaning).
In other instances, the functional element of the machine that is detachable can be a serving container such as a cup. In this case, the cup can be connected to the main machine base so that a fluid can be directly dispensed from the machine to the cup, from the bottom of said cup. More precisely, the cup bottom part comprises a fluid valve means for establishing a fluid connection with the main machine base in a leak-tight manner. Once the cup is connected to the machine, the user can start a brewing cycle, and a beverage such as coffee for instance is produced within the machine main base, which is then pumped and filled through the fluid valve means into the cup, from below said cup (filling of the cup is done from below). When the cup is filled, the consumer can detach the cup from the main machine base and use it as a normal cup for drinking. Such a configuration is very appealing.
In yet other instances, the detachable functional element can be a water reservoir that needs to be plugged/unplugged from the main machine base, through a leaktight fluid communication port.
In all instances known today, when a beverage preparation machine comprises a detachable functional element (i.e. an element that is necessary to conduct the correct functioning of the machine from the ingredients to the dispensing of the finished product to the serving container), said machine comprises complex means to attach and detach the functional element from the main machine base. For instance, such means can involve, cams, levers, hooks, locks and other similar mechanical means. Such means are complex and therefore expensive to manufacture, and also they are somehow complex to use for the consumer as they require several handling steps to unlock, unscrew, etc. Last but not least, their complex construction is an obstacle to easy maintenance and cleaning, and some of them can be subject to breakage after a certain time, due to the wearing of the mechanical parts. This is of course undesirable to the consumer.
There is therefore a need for a flowable food, or beverage preparation machine that comprises at least one detachable functional element, that obviates the disadvantages of the known systems.